Switch statement tests

[samsinsane]

I encountered this bug the other day in both Chrome and Firefox, and I'm not entirely sure what to do about it. The default case is not executed in this scenario:

switch(0)
{
  default:
    ...
}

Bit of backstory: At work we use Shader Conductor to convert our DirectX shaders to Metal, OpenGL, and OpenGL ES/WebGL shaders. This pattern seems to be generated due to functions being inlined into main, and the functions with multiple returns end up generating this switch statement. For what it's worth, this pattern worked fine for OpenGL on Windows, and Metal on macOS.

I was able to workaround this issue by replacing default with case 0, but figured I should at least report this somewhere and I stumbled across this repo while trying to find out if this was "by design" in WebGL. Since I couldn't find anything saying that default statements can be ignored under certain conditions, and since it seems to be browser independent, I figure that it's a conformance test problem and should be reported here? Unfortunately, I don't really have that much time to dedicate to this, so chasing individual browser vendors around on this isn't feasible, but I can add more tests to switch-case.html if that gets the ball rolling?

[kenrussell]

This sounds like a bug. Yes, please create a pull request adding more tests to switch-case.html.

Please also provide the contents of about:gpu from Chrome or about:support from Firefox on the machines where this isn't working. That will help narrow down whether this is a browser, shader translator, OS-specific, or graphics driver problem. Thanks.

[samsinsane]

This sounds like a bug. Yes, please create a pull request adding more tests to switch-case.html.

No worries, I can do that.

Please also provide the contents of about:gpu from Chrome or about:support from Firefox on the machines where this isn't working.

Both have a "Copy to Clipboard" button which seems to contain significantly less information but seems more inline with what you want? Is this the data that I should post, or do you need the full thing, tables and all?

[kainino0x]

In chrome at least, the button should include everything (it just uses JS to select-all and copy).

[samsinsane]

Strange, it seems to be copying more than 7 lines today, I must have done something wrong yesterday. I've attached the reports here:
HomeDesktopFirefox.txt
HomeDesktopChrome.txt
WorkLaptopChrome.txt

[kenrussell]

Thanks for the new tests; they've been merged now. Filed http://crbug.com/angleproject/4807 about this; Microsoft indicates that a workaround in ANGLE's shader translator is probably the best bet.

Closing this issue since the tests are in place and there's an ANGLE bug tracking potential workarounds.

[samsinsane]

@kenrussell Thanks for merging the PR and adding the ANGLE bug link! 😄